1. Field of the Invention
The present invention relates to a sheet stacking device for a sheet handling system, comprising at least one sheet entrance pathway for receiving incoming sheets; a sheet output unit with at least one output tray for stacking the received sheets to form at least one stack on the at least one output tray; and a control unit configured to determine the weight of the stack on the at least one output tray and for providing a control signal if the determined weight exceeds a predetermined value.
The present invention further relates to a method and a computer program product for controlling a sheet stacking device of a sheet handling system.
2. Background of the Invention
A sheet stacking device of this kind is known for example from JP 2002-326763 A and is used as an output device for sheet handling systems, for example in connection with printers, printing presses and photocopiers.
Sheets of the handled material, which can for example be paper or plastic foil, are stacked onto each other on one or more output trays, also called output bins. The stacked sheets can then be taken from the output trays for further processing.
Known sheet stacking devices usually comprise sensors for determining the stacking height. The determined height is then used to control the stacking device and/or a preceding sheet processing device in order to prevent an overflow of the output stack. Controlling can comprise stopping or postponing the delivery of further sheets to the sheet stacking device until the actual output tray has been emptied, or selecting a different output tray.
Depending on the sheet material used, the weight of an output stack can exceed a maximum weight that is allowed for further processing. This is particularly relevant for output trays that have a high sheet output capacity. A maximum allowed weight for stacks might be due to health and safety regulations or due to limitations imposed by following process stations.